Update es_AR.lang

I made some adjustments after trying the 1.8 additions in game. I also fix some "out of the GUI" texts [stuff in Spanish gets longer] of 1.8 and older updates.  

Also, is there way to add translations for the new ramdomly generated books? I feel people who don't speak English would be missing a lot. 

Best regards, 

Inés.
Merge pull request #174 from ines-aguirre/patch-3

Update es_AR.lang